The present invention relates in general to internal combustion engines operating with self-ignition and in particular to a device for modifying operational condition of a fuel metering system in the engine, the system including means for sensing at least one operational variable of the engine, an end stage regulator for setting fuel quantity, and control means connected to the sensing means for producing a first nominal setting signal.
A motor vehicle due to the elastic suspension of the engine on the vehicle body represents an oscillatory structure which in the occurrence of a disturbance can be induced into more or less damped oscillations. Such disturbances result for example from a jump in the fuel quantity introduced by the fuel metering system of the engine or can result from external influences for example due to sudden jump of the vehicle caused by a pothole in the road. The resulting oscillations which are manifested by changes of rotary speed of the engine or by relative movements between the engine and the body of the vehicle are normally in the frequency range between 1 and 8 Hertz and are termed as jolting or jerking of the vehicle.
In the U.S. patent application Ser. No. 513,984 a device for damping jolting oscillations in an internal combustion engine with self-ignition is described. In this prior art device a regulating circuit is installed between a control unit for a nominal value and the control mechanism for fuel quantity metering of an injection pump. The regulating circuit by means of signals derived from the rotary speed of the engine and of the position of the fuel quantity setting mechanism influences the fuel metering for the engine in such a manner that the jolting vibrations are strongly damped.
The disadvantage of this prior art device is the fact that the regulating system requires relatively high expenditures for circuit elements. In addition, it requires for its operation a mutual adjustment of a relatively large number of operational variables of the engine. As a consequence, this known device cannot be additionally installed in standard fuel metering systems of the engine.